There has recently been developed a "flip-chip" method for packaging semiconductor chips. The flip-chip method produces a small semiconductor package in which a semiconductor chip is bonded to a mount board. Typically, solder bumps are formed on the electrode pads of the semiconductor chip, and the solder bumps are connected to the pads and wiring of the mount board. A resin is filled in a gap between the semiconductor chip and the mount board to secure the package. FIG. 1 shows a conventional method of fabricating a semiconductor package that has a semiconductor chip and a mount board connected in a flip-chip manner with a resin filled in the gap between the semiconductor chip and the mount board. As shown, a semiconductor chip 1 is flip-chip-connected to a mount board 2, and a syringe 3 is moved along one side of the semiconductor chip 1 in the direction indicated by the arrow in the figure.
As the syringe is moved along the chip, a resin 4 contained in the syringe 3 is fed (i.e., potted) from the distal end of a nozzle 5. Ideally, the resin 4 would gradually fill the entire gap between the semiconductor chip 1 and mount board 2 by virtue of a capillary phenomenon, as shown in FIGS. 2A to 2C. However, the rate at which the resin enters the gap between the chip and mount board is typically lower than the rate at which the resin advances around the periphery of the semiconductor chip. Thus, using the conventional method, it is difficult to completely fill the gap between the semiconductor chip and the mount board.
FIGS. 3A to 3C show see-through views of the semiconductor chip to illustrate how the resin typically enters the gap between the semiconductor chip and mount board when the conventional method is used. Initially, as shown in FIG. 3A, a resin 4 is deposited along one side of the semiconductor chip 1. The mount board 2 has a substantially flat surface and a substantially uniform in-plane temperature distribution, so the rate at which the resin enters the gap is lower than the rate at which the resin advances around the periphery of the semiconductor chip, as shown in FIG. 3B. Consequently, the resin may fail to completely fill the gap, and instead enclose air (or peripheral atmosphere) so that a void 6 is formed, as shown in FIG. 3C. The void 6 lowers the grade and quality of the semiconductor device because it can lead to defects or cracks. More specifically, moisture entering the void can deteriorate the solder bridge, short-circuit the wiring elements on the mount board, or crack the semiconductor device.
As explained above, when the conventional method is used, resin-less voids tend to form in the gap between the semiconductor chip and the mount board, and thus the grade and quality of the resultant semiconductor device are lowered.